Plastic brain A varied life helps improve the brain, according to a study comparing wild and captive mole-rats.

The international study, led by Associate Professor Martin Whiting at Macquarie University, shows the brain's cognitive performance is negatively affected by extended periods of low stimulation in confined surroundings.

It also provides further evidence that the brain is more 'plastic' than thought, and adds weight to evidence that males have better navigational abilities than females.

Published recently in the journal Animal Cognition, the study compares the spatial cognitive abilities of wild mole-rats with those held captive in a laboratory for a long time.

The team, which also included researchers from South Africa and Canada, collected 14 male and 10 female adult Natal mole-rats (Cryptomys hottentotus natalensis) from Glengarry park in KwaZulu-Natal Province in South Africa.

Another 12 male and female mole-rats that had been kept in captivity for between 16 and 18 months were added to the study group.

Whiting says mole-rats were chosen for the experiment because they live in a subterranean burrow system that requires a degree of learning to navigate, similar to the maze-style approach needed for the test.

The mole-rats were made to navigate through a maze of tunnels covering an area of one metre by 1.2 metres with each animal undertaking the trial five times each day for three consecutive days.

Wild winners

The wild mole-rats completed the navigation task in less time than their captive counterparts, making fewer mistakes and covering less distance.

Whiting says the findings suggest the greater complexity of their habitation in the wild plays a role in stimulating cognitive development, shows brain plasticity - the 'use it or lose it' paradigm - at work.

"[The study] is pretty convincing for showing if you are not using that part of the brain it can regress," says Whiting.

He adds the reverse was also true, in that areas of the brain in constant demand could expand.

"In breeding season, for example, some regions of the brain might be larger," says Whiting. "But if you are an animal in a simple environment and not using the brain to navigate you are going to regress."

The researchers were surprised to find a marked difference between the spatial cognitive ability of the males and females

"We didn't predict this result because the subterranean complex [of the mole-rat] is so well defined," Whiting says.

"It might be the case males are more likely to disperse during breeding season and therefore have an increased ability to navigate and sense direction."

Whiting says the study is significant because it "demonstrates you do require stimulation to maintain cognitive performance".

Following on from that, he says, it reinforces the need for captive populations in institutions such as zoos, to provide enrichment and stimulation for their animals.